Just to try to tighten this up a little...
Let's just assume, for the sake of argument that:
1. A glider, which is properly equipped for the operation under the applicable regulations, is operating in a geographic area and at an altitude where the pilot of that glider has the right to operate;
2. An air carrier aircraft is also operating properly within the applicable regulations in the vicinity of the glider; and,
3. The air carrier must, under the rules, yield right-of-way to the glider.
In the US (yes, I know this wasn't in the US, but speaking conceptually...), the right-of-way rules are expressed in:
§ 91.113 Right-of-way rules: Except water operations.
(a) Inapplicability. This section does not apply to the operation of an aircraft on water.
(b) General. When weather conditions permit, regardless of whether an operation is conducted under instrument flight rules or visual flight rules, vigilance shall be maintained by each person operating an aircraft so as to see and avoid other aircraft. When a rule of this section gives another aircraft the right-of-way, the pilot shall give way to that aircraft and may not pass over, under, or ahead of it unless well clear.
(c) In distress. An aircraft in distress has the right-of-way over all other air traffic.
(d) Converging. When aircraft of the same category are converging at approximately the same altitude (except head-on, or nearly so), the aircraft to the other's right has the right-of-way. If the aircraft are of different categories --
(1) A balloon has the right-of-way over any other category of aircraft;
(2) A glider has the right-of-way over an airship, airplane, or rotorcraft; and
(3) An airship has the right-of-way over an airplane or rotorcraft.
OK. So you're flying a glider and God is on your side. However, God, to my knowledge, has yet to envelope any gliders in a protective cloak in which operations may be undertaken with impunity. I mean, what are you going to say as that 73 bears down on you? "Yeah. I see him. But he can't hit us. It's illegal for him to hit us." Perhaps true, but certainly an impractical approach to fostering aviation safety.
With apologies to Roger Waters, I can imagine that a conversation between the two occupants of the glider, having survived the collision, would go something like this as they fell to their deaths:
"I certainly was in the right!"
"you was definitely in the right. that geezer was cruising for a
Bruising!"
Of course, then they die.
So, guess what? The glider guys are correct: they have every right to do what they do so long as it comports with the rules. Further, the heavier-metal guys are also right: if you're in a glider you've GOT to take-on more responsibility than the regs perhaps demand. However, let's not continue to beat on this as a "conform to the rules" argument, because even a strict adherence to the rules isn't enough in aviation in general. If you're going to work to change the rules, that's fine. However, if we're talking about things AS THEY EXIST, then let's be a little more practical about keeping airframes apart and little less pragmatic when it comes to betting your life on the rules.
Rant over.
Dave